One reporting period. Two compliance requirements. Scope 3 is the exception.

11 Aug 2026

Lili Boyle, Senior Sustainability Consultant at Inteb, on the best 12 month window that can serve two compliance pieces at once, and why no amount of planning can make Scope 3 reporting any less demanding.

Between now and December 2027, many large UK organisations will find themselves navigating several sustainability reporting requirements at the same time. Annual Streamlined Energy and Carbon Reporting (SECR) disclosures must continue as part of the Directors’ Report, whilst ESOS Phase 4 requires organisations to submit their compliance notification by 5th December 2027. Alongside these existing obligations, the proposed UK Sustainability Reporting Standards (UK SRS) are expected to become mandatory for around 500 listed companies from January 2027, with wider consultation for private companies anticipated to follow. At the same time, organisations are increasingly focusing on Scope 3 emissions. Whilst Scope 3 is not currently a regulatory requirement, it is often proving to be the most resource-intensive aspect of sustainability reporting.

In practice, these responsibilities are frequently managed by the same sustainability or compliance professional. Although each framework has different reporting requirements, they are underpinned by much of the same information. Energy consumption and transport fuel data support both SECR and ESOS reporting, whilst procurement and spend data form the basis of Scope 3 calculations. Recognising where these overlaps exist allows organisations to reduce duplication and make better use of the data they are already collecting.

One dataset, flagged and annotated once, feeding two separate output documents. This is what collect once, report twice looks like before anyone has written a single line of the directors’ report or the ESOS audit evidence.

Collect once, report twice

One of the simplest opportunities lies in aligning reporting periods. SECR typically follows an organisation’s financial year because the disclosure forms part of the Directors’ Report submitted alongside statutory accounts. ESOS, by comparison, requires organisations to select a 12-month reference period that includes the qualification date of 31 December 2026 and concludes before the compliance deadline of 5th December 2027.

For many organisations, these requirements naturally overlap. Selecting the financial year that contains 31st December 2026 as the ESOS reference period enables the same dataset to support both reporting obligations. Organisations with December or a typical tax year end generally have sufficient time between the end of the reporting period and the ESOS deadline to complete the assessment. September year ends remain achievable but allow considerably less preparation time. October and November year ends require more careful planning, as the reporting period finishes only weeks, or in some cases days, before the ESOS submission deadline. In these circumstances, selecting an alternative ESOS or SECR reference period may provide a more practical solution.

This alignment is not built into the regulations. Government considered further harmonisation between ESOS and SECR but chose not to proceed, and the proposed UK Sustainability Reporting Standards will operate alongside existing requirements rather than replacing them. Organisations therefore need to make conscious decisions about how they structure their reporting, rather than expecting the reporting frameworks to align automatically.

The Scope 3 exception

Whilst reporting periods can often be coordinated, the same cannot always be said for the data collection itself. Energy data is generally collected from invoices, meter readings and utility systems, making it relatively straightforward to manage once robust processes are established. Scope 3 emissions present a different challenge.

Spend-based Scope 3 reporting relies on detailed purchase ledger data, with every transaction requiring classification into the appropriate emissions category. This is rarely a fully automated process. During one recent project, we reviewed more than 40,000 individual ledger lines to ensure they were accurately categorised and capable of meeting external audit requirements. Although carbon accounting software plays an important role in storing data and producing reports, it cannot replace professional judgement. Transactions often require interpretation before they can be allocated correctly, particularly where descriptions provide limited information.

The legal sector arrived at integrated sustainability reporting early, not because it was ahead of the curve on ESG, but because it already understood how to manage large volumes of compliance documentation across multiple simultaneous obligations. The skills transferred.

Why the legal sector got here first

The legal sector provides a useful example of how this challenge is evolving. Over the past eighteen months, a growing number of law firms have started to measure their supply chain emissions in response to increasing client expectations and sector-wide initiatives. For professional services organisations, Scope 1 and Scope 2 emissions often represent only a small proportion of their overall environmental impact, with the majority arising through purchased goods and services. Measuring Scope 3 therefore provides a much more complete understanding of organisational emissions.

Industry expectations have also continued to develop. Initiatives such as the Legal Sustainability Alliance and Legal Charter 1.5 have encouraged firms to strengthen their sustainability reporting, whilst many corporate clients now request Scope 3 emissions data as part of procurement and panel review processes. As more organisations measure their own supply chain emissions, they increasingly require the same information from their suppliers, creating a cascading effect throughout the supply chain.

Which is why the answer is capacity, not advice

This growing demand means that the challenge is often less about technical knowledge and more about organisational capacity. Many organisations already understand what needs to be done but lack the time or resource to complete large-scale data reviews alongside their day-to-day responsibilities. Detailed spend analysis can require weeks of focused work, particularly where external assurance or ISO standards apply.

For this reason, additional project support is often more valuable than strategic advice alone. Integrating specialist resource into an existing sustainability team allows organisations to complete defined pieces of work during peak reporting periods without increasing permanent headcount. Once the reporting cycle is complete, that additional resource is no longer required, making it a practical solution for workloads that naturally fluctuate throughout the year.

Starting an integrated SECR and ESOS programme means putting the deadlines on the board first, then working backwards. The cards go up empty and get filled in as the data collection plan takes shape around the dates that cannot move.

Where to start

Ultimately, successful sustainability reporting begins with forward planning. Selecting an appropriate reporting period can significantly reduce duplicated effort, but organisations should also recognise where substantial time commitments remain unavoidable. Whilst aligning reporting windows may take only a short period of planning, accurately calculating Scope 3 emissions requires considerably greater investment in data review and interpretation. Understanding that distinction early enables organisations to allocate resources effectively and avoid unnecessary pressure as reporting deadlines approach.

FAQ’s

Can I use the same data for SECR and ESOS?

Yes, if you choose the reference period deliberately. SECR is typically based on your financial year. Your ESOS Phase 4 reference period must be 12 consecutive months that include 31st December 2026 and close before 5th December 2027. The most useful financial year contains 31st December 2026 and satisfies both, so the same data set can serve each report.

Which financial year should I use as my ESOS Phase 4 reference period?

The one containing 31st December 2026. For a December year end, that is calendar 2026. For a typical tax year end, we look at April 2026 to March 2027. Any financial year that straddles the qualification date will be able to collect once and report twice.

What if my financial year ends in October or November?

This is the case to watch. An October year end closes on 31st October 2027, leaving roughly five weeks before the ESOS deadline of 5th December 2027. A November year end closes on 30th November 2027, leaving five days, which is not workable in practice. In both cases you will probably need a separate ESOS reference period, such as calendar year 2026, and you should decide that early.

Does UK SRS replace SECR?

No. The Department for Business and Trade confirmed in January 2026 that SECR continues alongside UK SRS as a separate annual obligation. They have different scopes and different policy aims. UK SRS S1 and S2 were published on 25th February 2026 for voluntary use, and the FCA has proposed making UK SRS S2 mandatory for around 500 listed companies from accounting periods beginning on or after 1st January 2027.

Do law firms have to comply with SECR?

Large LLPs fall within SECR, and most UK law firms of any size are LLPs that meet the Companies Act definition of large. So these organisations will already be reporting on energy and carbon before the Scope 3 work even begins.

Why are law firms measuring Scope 3 emissions?

For a professional services business, Scope 3 is effectively their entire carbon footprint. Offices and utilities produce very little by comparison. The sector is also being pulled along by the Legal Sustainability Alliance and Legal Charter 1.5 and, pushed by corporate clients who ask for emissions data during panel reviews, since their own Scope 3 includes the legal services they buy.

Can software calculate Scope 3 emissions from spend data?

Only partly. Carbon accounting platforms hold the data and produce the report at the end. What they cannot do is accurately decide which category a given line of the purchase ledger belongs in. On large projects that categorisation is still a manual review, line by line, and it is the single most labour intensive part of the exercise.